1. Field of the Invention
The present invention relates to an inkjet head for printing by ejecting ink onto a recording medium.
2. Description of the Related Art
In an inkjet printer or the like, an inkjet head distributes ink supplied from an ink tank to a plurality of pressure chambers, and selectively applies pressure pulses onto the respective pressure chambers, thereby ejecting ink out of nozzles. In some cases, an actuator unit, which is configured by laminating a plurality of piezoelectric sheets made of piezoelectric ceramics, is employed as a member for selectively applying pressure to the pressure chambers.
As an example of such an inkjet head, an inkjet head having a plurality of actuator units configured by sandwiching a continuous flat piezoelectric sheet between a common electrode and a plurality of individual electrodes has been known (see JP-A-2003-311953). The common electrode is formed so as to extend over a plurality of pressure chambers. The plurality of individual electrodes are configured by main electrode sections disposed so as to oppose the respective pressure chambers, and auxiliary electrode sections to which voltage is applied from the outside. When the individual electrode is set to be of a different potential from that of the common electrode upon supply of driving voltage from a flexible printed circuit (FPC), a portion of the piezoelectric sheet, which is sandwiched between the individual electrodes and the common electrode and which is polarized in the lamination direction, is expanded or contracted in the lamination direction by a so-called longitudinal piezoelectric effect. Accordingly, the volume of the pressure chamber is changed, thereby enabling ejection of ink from a nozzle communicating with the pressure chamber toward a recording medium. In addition, in a single actuator unit, all the individual electrodes are configured such that all the auxiliary electrode sections are formed on the same side with respect to the main electrode sections and facing a one direction. Meanwhile, on the FPC which is to be connected to the auxiliary electrode sections, a plurality of connecting pads (terminals) are formed in correspondence to the arrangement of the respective auxiliary electrode sections.